3/4 days late negative hpt

My last menstrual cycle was 2/19/14 and it lasted for a few days. I had intercourse during my fertile days 2-3 days before ovulation. I am now going on 4 days late and I'm having light cramps, tender breasts, and slight nausea. I also noticed my breast have a blue vein I've never noticed before. I tested the day of my expected period and a week before and they were both negative.